Multiple-input multiple-output (MIMO) spread-spectrum system and method

ABSTRACT

A system and method for transmitting a plurality of spread-spectrum signals over a communications channel having fading. The plurality of spread-spectrum signals are radiated by a plurality of antennas, with each antenna preferably spaced by one-quarter wavelength. A plurality of receiver antennas receive the plurality of spread-spectrum signals and a plurality of fading spread-spectrum signals. Each receiver antenna is coupled to a plurality of matched filters having a respective plurality of impulse responses matched to the chip-sequence signals of the plurality of spread-spectrum signals. A RAKE and space-diversity combiner combines, for each respective chip-sequence signal, a respective plurality of detected spread-spectrum signals and a respective multiplicity of detected-multipath-spread-spectrum signals, to generate a plurality of combined signals. The symbol amplitudes can be measured and erasure decoding employed to improve performance.

RELATED PATENTS

This patent is a continuation of application Ser. No. 10/254,461, filedSep. 25, 2002, now U.S. Pat. No. 6,757,322 and stems from a continuationapplication of U.S. patent application Ser. No. 09/665,322, and filingdate of Sep. 19, 2000 now U.S. Pat. No. 6,466,610, entitledSPREAD-SPECTRUM SPACE DIVERSITY AND CODING ANTENNA SYSTEM AND METHOD,with inventor DONALD L. SCHILLING, and a continuation application ofU.S. patent application Ser. No. 09/198,630, and filing date of Nov. 24,1998, entitled EFFECT SHADOW REDUCTION ANTENNA SYSTEM FOR SPREADSPECTRUM, with inventor DONALD L. SCHILLING which issued on Oct. 3,2000, as U.S. Pat. No. 6,128,330. The benefit of the earlier filing dateof the parent patent application is claimed for common subject matterpursuant to 35 U.S.C. § 120.

BACKGROUND OF THE INVENTION

This invention relates to antennas, and more particularly to reducingthe effects of shadowing from a multipath environment, using spacediversity and coding.

DESCRIPTION OF THE RELEVANT ART

Data sent from terminal to base, or vice versa, are often shadowed.Shadowing is a function of time, and may be caused by buildings,foliage, vehicles, people, motion of the terminal, etc. Shadowing is theblocking, or attenuating, of the transmitted signal. Shadowing may occurin fixed or mobile systems, and can vary slowly or quickly depending onthe situation.

While shadowing has an effect which is similar to multipath, the causesand statistics of shadowing may be very different. For example, thepresence of a building may result in total shadowing, independent oftime, while multipath, caused by numerous multipath returns, produces aRayleigh or Ricean fading distribution. Fading due to shadowing andmultipath may be reduced by adding a receiver antenna to increasereceiver diversity.

Coding techniques using space diversity as well as time, are known as“space-time” codes. In the prior art, with a multiple antenna system,the input to each receive antenna is assumed to have Rayleigh fading. Aproblem with multiple antenna systems is that a particular antennaoutput may be shadowed by 6 dB or more to a particular receive antenna.Such shadowing leaves the other antennas to receive a desired signal,effectively destroying one source of data.

SUMMARY OF THE INVENTION

A general object of the invention is to reduce the effects of shadowingand multipath in a fading environment.

Another object of the invention is to improve performance of aspread-spectrum communications system.

An additional object of the invention is to increase capacity of aspread-spectrum communications system.

A further object of the invention is to minimize fading and enhanceoverall performance in a spread-spectrum communications system.

According to the present invention, as embodied and broadly describedherein, an antenna system is provided employing space diversity andcoding, for transmitting data having symbols, over a communicationschannel. The transmitted signal passes through a communications channelhaving fading caused by multipath as well as shadowing.

In a first embodiment of the invention, the antenna system comprises aforward error correction (FEC) encoder, an interleaver, a demultiplexer,a plurality of spread-spectrum devices, a plurality of transmitantennas, and a plurality of receiver subsystems. Each receiversubsystem includes a receiver antenna and a plurality of matchedfilters. The receiver system further includes a RAKE and space-diversitycombiner, a multiplexer, a de-interleaver, and a decoder.

The FEC encoder encodes the data using an error correction code togenerate FEC data. The interleaver interleaves the symbols of the FECdata to generate interleaved data. The demultiplexer demultiplexes theinterleaved data into a plurality of subchannels of data. The pluralityof spread-spectrum devices, spread-spectrum processes the plurality ofsubchannels of data with a plurality of chip-sequence signals,respectively. Each chip-sequence signal of the plurality ofchip-sequence signals is different from other chip-sequence signals inthe plurality of chip-sequence signals. The plurality of spread-spectrumdevices thereby generates a plurality of spread-spectrum subchannelsignals, respectively. The plurality of transmit antennas radiate, at acarrier frequency using radio waves, the plurality ofspread-spectrum-subchannel signals over a communications channel as aplurality of spread-spectrum signals. The plurality of spread-spectrumsignals could use binary phase-shift-keying (BPSK) modulation,quadrature phase-shift-keying (QPSK) modulation, differential encoding,etc., and other modulations, which are all well known carrier modulationtechniques.

The communications channel imparts fading on the plurality ofspread-spectrum signals. The multipath generates a multiplicity offading spread-spectrum signals. The fading also may include shadowing.

The plurality of receiver subsystems receive the plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals from the communications channel. Each receiver subsystem has thereceiver antenna for receiving the plurality of spread-spectrum signals,and the plurality of matched filters. Each receiver antenna in theplurality of receiver antennas is spaced from other receiver antennas inthe plurality of receiver antennas preferably by at least one-quarter(¼) wavelength, and preferably as far apart as practicable. The presentinvention includes spacings less than one-quarter wavelength, but withdegradation in performance The plurality of matched filters has aplurality of impulse responses matched to the plurality of chip-sequencesignals, respectively. The plurality of matched filters detect theplurality of spread-spectrum signals and the multiplicity of fadingspread-spectrum signals, as a plurality of detected spread-spectrumsignals and a multiplicity of detected-fading spread-spectrum signals,respectively.

A plurality of RAKE and space-diversity combiners combine the pluralityof detected spread-spectrum signals and the multiplicity of thedetected-fading spread-spectrum signals from each of the plurality ofreceiver subsystems, to generate a plurality of combined signals. Amultiplexer multiplexes a plurality of combined signals therebygenerating the multiplexed signal. The de-interleaver de-interleaves themultiplexed signal from the multiplexer, and thereby generatesde-interleaved data. The decoder decodes the de-interleaved data.

As an alternative, a preferred embodiment is to select the receivedversion of each received chip-sequence signal at each antenna andcombine them in a RAKE. In this embodiment, the space and time combiningof each channel from a respective chip-sequence signal occur in a singleRAKE receiver. The total number of RAKE receivers is equal to the numberof chip-sequence signals, or one or more RAKEs could be time multiplexedto represent the number of chip-sequence signals.

A second embodiment of the invention has an antenna system fortransmitting data having symbols over the communications channel havingfading caused by multipath and shadowing. In the second embodiment ofthe invention, as previously described for the first embodiment of theinvention, a multiplicity of delay devices is coupled between theinterleaver and the plurality of spread-spectrum devices, respectively.A first signal of the plurality of signals of the interleaved data neednot be delayed. The other signals of the plurality of signals ofinterleaved data are delayed, at least one symbol, one from the other,by the multiplicity of delay devices. Each delay device of themultiplicity of delay devices has a delay different from other delaydevices of the multiplicity of delay devices relative to the firstsignal. The multiplicity of delay devices thereby generate a pluralityof time-channel signals.

The plurality of spread-spectrum devices has a first spread-spectrumdevice coupled to the interleaver, and with the other spread-spectrumdevices coupled to the multiplicity of delay devices, respectively. Theplurality of spread-spectrum devices spread-spectrum process, with aplurality of chip-sequence signals, the first signal and the pluralityof time-channel signals as a plurality of spread-spectrum signals. Theplurality of transmit antennas radiate at the carrier frequency, usingradio waves, the plurality of spread-spectrum signals over thecommunications channel.

The communications channel imparts fading due to multipath and shadowingon the plurality of spread-spectrum signals. The multipath generates amultiplicity of fading spread-spectrum signals.

The plurality of receiver subsystems receive the plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals from the communications channel. Each receiver subsystemincludes a receiver antenna for receiving the plurality ofspread-spectrum signals and a plurality of matched filters; theplurality of matched filters has a plurality of impulse responsesmatched to the plurality of chip-sequence signals, respectively. Theplurality of matched filters detects the plurality of spread-spectrumsignals and the multiplicity of fading spread-spectrum signals, as aplurality of detected spread-spectrum signals and a multiplicity ofdetected-fading spread-spectrum signals.

A RAKE and space-diversity combiner combines the detectedspread-spectrum signal and the multiplicity of detected-fadingspread-spectrum signals from each of the plurality of receiversubsystems. This generates a plurality of combined signals. The FECdecoder decodes the de-interleaved signal as decoded data.

Additional objects and advantages of the invention are set forth in partin the description which follows, and in part are obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention also may be realized and attained bymeans of the instrumentalities and combinations particularly pointed outin the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the specification, illustrate preferred embodiments of theinvention, and together with the description serve to explain theprinciples of the invention.

FIG. 1 is a block diagram of a four code transmitter, using fourantennas;

FIG. 2 is a block diagram of a four code transmitter, using fourantennas and separate FEC encoders and bit interleavers for eachchannel;

FIG. 3 is a block diagram of a receiver system having four antennas,with four matched filters per antenna;

FIG. 4 is a block diagram of a transmitter having two codes and twoantennas, and a delay on data;

FIG. 5 is a block diagram of a transmitter having two codes and twoantennas, and a delay on data, with a separate FEC encoder and bitinterleaver for each channel;

FIG. 6 is a block diagram of a receiver system having two receiverantennas, and two matched filters per antenna; and

FIG. 7 is a block diagram of a receiver having three antennas and threerake and space combiners, coupled to a multiplexer.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference now is made in detail to the present preferred embodiments ofthe invention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals indicate like elementsthroughout the several views.

The present invention provides a novel approach for reducing the effectof fading due to shadowing and multipath, through the use of multipleantennas at the terminal and also at the base station, as well as asingle RAKE/maximal ratio combiner to combine all time and spacesignals. Previous solutions have assumed multiple antennas at the base,where space diversity is then applied. Also, each antenna receiver hasan individual RAKE. Placing multiple antennas at the terminal, however,can result in a significant improvement in system performance. The useof maximal ratio combining, RAKE and erasure decoding further enhancesystem performance.

As illustratively shown in FIGS. 1–6, the present invention broadlyincludes an antenna system employing time (RAKE) and space (antenna)diversity and coding of spread-spectrum signals. The antenna system isfor transmitting data having symbols over a communications channel. Thesymbols may be bits, or may be based on pairs of bits or groups of bits.The communications channel is assumed to have fading due to multipathand shadowing.

The antenna system broadly includes forward error correction (FEC)means, interleaver means, demultiplexer means, spread-spectrum means, aplurality of transmit antennas, a plurality of receiver subsystems, RAKEand space-diversity means, multiplexer means, de-interleaver means, anddecoder means. Each receiver subsystem includes receiver-antenna meansand matched-filter means.

The interleaver means is coupled between the demultiplexer means and theFEC means. The spread-spectrum means is coupled between thedemultiplexer means and the plurality of transmit antennas.Alternatively, the FEC means is coupled between the demultiplexer meansand the interleaver means, and the spread-spectrum means is coupled tothe interleaver means. The communications channel is between theplurality of transmit antennas and the plurality of receiver subsystems.

Each receiver subsystem has receiver-antenna means exposed to thecommunications channel. The matched filter means is coupled to thereceiver-antenna means.

The RAKE and space-diversity means is coupled to each matched filtermeans of the plurality of receiver subsystems, and the multiplexer meansis coupled to the RAKE and space-diversity means. The de-interleavermeans is coupled to the RAKE and space-diversity means, and the decodermeans is coupled to the de-interleaver means.

The FEC means FEC encodes the data, thereby generating FEC data. FECdata is defined herein to be FEC encoded data. Forward-error-correctionencoding is well known in the art, and the use of a particular FEC codeis a design choice. The interleaver means interleaves symbols of the FECdata, thereby generating interleaved data. Interleaved data is definedherein to be interleaved FEC data. Interleaving, as is well known in theart, randomizes the errors. The demultiplexer means demultiplexes theinterleaved data into a plurality of subchannels of data.

The spread-spectrum means spread-spectrum processes the plurality ofsubchannels of data with a plurality of chip-sequence signals,respectively. Each chip-sequence signal is different from otherchip-sequence signals in the plurality of chip-sequence signals. Thespread-spectrum means thereby generates a plurality ofspread-spectrum-subchannel signals, respectively. Eachspread-spectrum-subchannel signal is defined by a respectivechip-sequence signal. In a preferred embodiment, each chip-sequencesignal is designed to be orthogonal to other chip-sequence signals inthe plurality of chip-sequence signals, when received at the receiver,neglecting multipath. In practice, however, orthogonality may not berealized.

The plurality of transmit antennas has each transmitter antenna spacedfrom other antennas in the plurality of transmit antennas, preferably byat least a quarter wavelength at a carrier frequency. If the transmitterantennas are spaced by less than a quarter wavelength, performancedegrades. The present invention includes antennas spaced less than aquarter wavelength, with spacing of at least a quarter wavelength beinga preferred embodiment. The plurality of transmit antennas radiates atthe carrier frequency, using radio waves, the plurality ofspread-spectrum-subchannel signals, respectively, over thecommunications channel, as a plurality of spread-spectrum signals. Thecarrier frequency typically is the frequency of a carrier signalgenerated by an oscillator, as is well known in the art. The pluralityof spread-spectrum signals is mixed or multiplied by the carrier signal.Appropriate oscillator, mixer, amplifier and filter can be employed toassist radiating the plurality of spread-spectrum signals at the carrierfrequency. Various modulations, such as QPSK, BPSK, differentialencoding, etc., may be use as a carrier modulation for the plurality ofspread-spectrum signals.

The communications channel imparts fading due to multipath and shadowingon the plurality of spread-spectrum signals. The communications channelthereby generates a plurality of fading spread-spectrum signals.

The plurality of receiver subsystems receive the plurality ofspread-spectrum signals, arriving from the plurality of transmitantennas through the communications channel, and the multiplicity offading spread-spectrum signals from the communications channel. Withineach receiver subsystem, the receiver-antenna means receives a pluralityof spread-spectrum signals and the multiplicity of fadingspread-spectrum signals. The matched-filter means has a plurality ofimpulse responses matched to the plurality of chip-sequence signals,respectively. The matched-filter means detects the plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals, as a plurality of detected spread-spectrum signals and amultiplicity of detected-fading spread-spectrum signals, respectively.

The RAKE and space-diversity means combines the plurality of detectedspread-spectrum signals and the multiplicity of detected-fadingspread-spectrum signals from each of the plurality of receiversubsystems. The RAKE and space-diversity means thereby generates aplurality of combined signals.

The multiplexer means multiplexes the plurality of combined signals, asa multiplexed signal. The de-interleaver means de-interleaves themultiplexed signal from the multiplexer, thereby generating ade-interleaved signal. The decoder means decodes the de-interleavedsignal.

FIGS. 1–3 illustratively show a system with four transmit antennas TA1,TA2, TA3, TA4 and four receive antennas RA1, RA2, RA3, RA4. The numberof transmit antennas usually is not the same as the number of receiverantennas. In FIG. 1, the data are first forward-error-correction (FEC)encoded by FEC encoder 21 and interleaved by interleaver 22, and thendemultiplexed by demultiplexer 32 into four data streams. Theinterleaving, FEC encoding, demultiplexing process alters the systemperformance. Alternatively, as shown in FIG. 2, the data could first bedemultiplexed by demultiplexer 32 and then each data stream could be FECencoded by a plurality of FEC encoders 521, 621, 721, 821 andinterleaved by a plurality of interleavers 522, 622, 722, 822. Themultipath FEC/interleavers could be built as individual devices, or as asingle time-multiplexed device.

The first, second, third and fourth chip-sequence signals, g₁(t), g₂(t),g₃(t), and g₄(t), typically are pseudonoise (PN) spreading sequences.Since the transmit antennas are spaced more than one-quarter wavelengthwith respect to the carrier frequency, the chip-sequence signals can beadjusted to be orthogonal to a specific receiver antenna but not to allreceiver antennas simultaneously. Thus, orthogonality is not required.The antenna could be “smart”, e.g., steerable or phased array, however,ordinary omnidirectional antennas at the terminal are often mostpractical. Thus, on a car, omni-directional antennas may be preferred,while in an office or home, a directional antenna may be preferred.

In the exemplary arrangement shown in FIG. 1, the FEC means is embodiedas a forward-error-correction (FEC) encoder 21 and the interleaver meansis embodied as an interleaver 22. The demultiplexer means is embodied asa demultiplexer 32 and the spread-spectrum means is embodied as aplurality of spread-spectrum devices 23, 33, 43, 53, and a chip-sequencesignal generator 31. The spread-spectrum means alternatively may beembodied as an application specific integrated circuit (ASIC) with aplurality of matched filters, charged coupled devices (CCD) or,alternatively, surface-acoustic-wave (SAW) devices, as is well known inthe art. The interleaver 22 is coupled between FEC encoder 21 and thedemultiplexer 32. The plurality of spread-spectrum devices 23, 33, 43,53 is coupled to the chip-sequence signal generator 31, and between thedemultiplexer 32, and the plurality of transmit antennas TA1, TA2, TA3,and TA4.

The FEC encoder 21 encodes the data to generate FEC data. FEC encodingis well known in the art. A particular choice of an FEC encodingtechnique and code is a design choice. The interleaver 22 interleavesthe FEC data to generate interleaved data. The interleaver selection isa design choice. The demultiplexer 32 demultiplexes the interleaved datainto a plurality of subchannels of data.

In FIG. 2, the FEC means is embodied as a plurality of FEC encoders 521,621, 721, 821 and the interleaver means is embodied as a plurality ofinterleavers 522, 622, 722, 822. The demultiplexer 32 firstdemultiplexes the data into a plurality of sub-data streams. Theplurality of FEC encoders 521, 621, 721, 821 FEC encode the plurality ofsub-data streams into a plurality of FEC-sub-data streams, respectively.The plurality of interleavers 522, 622, 722, 822 interleave theplurality of FEC-sub-data streams into the plurality of subchannels,respectively.

In FIGS. 1 and 2, a chip-sequence generator 31 generates the pluralityof chip-sequence signals. A chip-sequence signal typically is generatedfrom a pseudonoise (PN) sequence, as is well known in the art. Eachchip-sequence signal is different from other chip-sequence signal in theplurality of chip-sequence signals. In an embodiment, each chip-sequencesignal may be orthogonal to other chip-sequence signals in the pluralityof chip-sequence signals.

The plurality of spread-spectrum devices 23, 33, 43, 53 spread-spectrumprocess the plurality of subchannels of data with the plurality ofchip-sequence signals, respectively. Each spread-spectrum-subchannelsignal of the plurality of spread-spectrum-subchannel signals is definedby a respective chip-sequence signal from the plurality of chip-sequencesignals. The plurality of spread-spectrum devices thereby generate aplurality of spread-spectrum-subchannel signals, respectively.

The plurality of transmit antennas TA1, TA2, TA3, TA4 has eachtransmitter antenna of the plurality of transmit antennas preferablyspaced from other antennas of the plurality of transmit antennaspreferably by at least a quarter wavelength at a carrier frequency. Thisprovides independence of transmitted signals. The plurality of transmitantennas TA1, TA2, TA3, TA4 radiate at the carrier frequency using radiowaves, the plurality of spread-spectrum-subchannel signals over thecommunications channel as a plurality of spread-spectrum signals.Appropriate oscillator product device and filter may be added to shiftthe plurality of spread-spectrum-subchannel signals to a desired carrierfrequency. Amplifiers may be added as required.

The communications channel imparts fading on the plurality ofspread-spectrum signals. The fading generates a multiplicity of fadingspread-spectrum signals, some of which may have shadowing and multipath.The shadowing may be from buildings, foliage, and other causes ofmultipath and shadowing.

The spread-spectrum processing typically includes multiplying theplurality of subchannels of data by the plurality of chip-sequencesignals, respectively. In an alternative embodiment, if a plurality ofmatched filters or SAW devices was employed in place of thespread-spectrum devices, then the plurality of matched filters or SAWdevices would have a plurality of impulse responses, respectively,matched to the plurality of chip-sequence signals, respectively. Ifprogrammable matched filters were employed, then the plurality ofimpulse responses of the plurality of matched filters may be set by theplurality of chip-sequence signals or other control signals, from thechip-sequence signal generator 31 or other controller.

At the receiver, the plurality of receiver subsystems receives theplurality of spread-spectrum signals and the multiplicity of fadingspread-spectrum signals from the communications channel. Each receiversubsystem of the plurality of receiver subsystem has a receiver antenna.As illustratively shown in FIG. 3, the plurality of receiver subsystemsincludes a plurality of receiver antennas RA1, RA2, RA3, RA4,respectively. The plurality of receiver antennas RA1, RA2, RA3, RA4 haseach receiver antenna of the plurality of receiver antennas preferablyspaced from other antennas of the plurality of receiver antennaspreferably by at least one-quarter wavelength at the carrier frequency.Each receiver subsystem may include receiver circuitry which amplifies,filters, translates and demodulates received signals to baseband or anintermediate frequence (IF) for processing by the matched filter. Suchreceiver circuitry is well known in the art.

Each receiver subsystem has a respective receiver antenna coupled to arespective plurality of matched filters. The first receiver subsystem,by way of example, has the first receiver antenna RA1 coupled to a firstplurality of matched filters 24, 34, 44, 54. The second receiver antennaRA2 is coupled to a second plurality of matched filters 25, 35, 45, 55.The third receiver antenna RA3 is coupled to a third plurality ofmatched filters 26, 36, 46, 56. The fourth receiver antenna RA4 iscoupled to a fourth plurality of matched filters 27, 37, 47, 57. Eachreceiver antenna in the plurality of receiver antennas RA1, RA2, RA3,RA4, receives a plurality of spread-spectrum signals and themultiplicity of fading spread-spectrum signals.

For each receiver antenna, as shown in FIG. 3, by way of example, theplurality of matched filters includes a matched filter having a impulseresponse MF1 matched to a first chip-sequence signal g₁(t); a matchedfilter having a impulse response MF2 matched to a second chip-sequencesignal g₂(t); a matched filter having an impulse response MF3 matched toa third chip-sequence signal g₃(t); and, a matched filter having animpulse response MF4 matched to a fourth chip-sequence signal g₄(t).More particularly, the first plurality of matched filters 24, 34, 44,54, in FIG. 3, has a first matched filter 24 with an impulse responseMF1 matched to a first chip-sequence signal g₁(t) in the plurality ofchip-sequence signals; a second matched filter 34 with an impulseresponse MF2 matched to a second chip-sequence signal g₂(t) in theplurality of chip-sequence signals; a third matched filter 44 with animpulse response MF3 matched to a third chip-sequence signal g₃(t) inthe plurality of chip-sequence signals; and a fourth matched filter withan impulse response MF4 matched to a fourth chip-sequence signal g₄(t)in the plurality of chip-sequence signals. The second plurality ofmatched filters 25, 35, 45, 55, in FIG. 3, has a fifth matched filter 25with an impulse response MF1 matched to the first chip-sequence signalg₁(t) in the plurality of chip-sequence signals; a sixth matched filter35 with an impulse response MF2 matched to the second chip-sequencesignal g₂(t) in the plurality of chip-sequence signals; a seventhmatched filter 45 with an impulse response MF3 matched to the thirdchip-sequence signal g₃(t) in the plurality of chip-sequence signals;and an eighth matched filter 55 with an impulse response MF4 matched tothe fourth chip-sequence signal g₄(t) in the plurality of chip-sequencesignals. The third plurality of matched filters 26, 36, 46, 56, in FIG.3, has a ninth matched filter 26 with an impulse response MF1 matched tothe first chip-sequence signal g₁(t) in the plurality of chip-sequencesignals; a tenth matched filter 36 with an impulse response MF2 matchedto the second chip-sequence signal g₂(t) in the plurality ofchip-sequence signals; an eleventh matched filter 46 with an impulseresponse MF3 matched to a third chip-sequence signal g₃(t) in theplurality of chip-sequence signals; and a twelfth matched filter 56 withan impulse response MF4 matched to a fourth chip-sequence signal g₄(t)in the plurality of chip-sequence signals. The fourth plurality ofmatched filters 27, 37, 47, 57, in FIG. 3, has a thirteenth matchedfilter 27 with an impulse response MF1 matched to the firstchip-sequence signal g₁(t) in the plurality of chip-sequence signals; afourteenth matched filter 37 with an impulse response MF2 matched to thesecond chip-sequence signal g₂(t) in the plurality of chip-sequencesignals; a fifteenth matched filter 47 with an impulse response MF3matched to the third chip-sequence signal g₃(t) in the plurality ofchip-sequence signals; and a sixteenth matched filter 57 with an impulseresponse MF4 matched to the fourth chip-sequence signal g₄(t) in theplurality of chip-sequence signals. Thus, each plurality of matchedfilters has a plurality of impulse responses MF1, MF2, MF3, MF4 matchedto the plurality of chip-sequence signals, g₁(t), g₂(t), g₃(t), g₄(t),respectively.

Alternatively, all four antennas could be coupled to a single radiofrequence (RF) RF-IF down converter, with in-phase and quadrature-phasecomponents being formed, and a single matched filer for each impulseresponse. Thus, there would be a single matched filter with the impulseresponse MF1, there would be a single matched filter with the impulseresponse MF2, there would be a single matched filter with the impulseresponse MF3, and there would be a single matched filter with theimpulse response MF4.

In FIG. 3, the first plurality of matched filters 24, 34, 44, 54, by wayof example, detects from the plurality of spread-spectrum signals andthe multiplicity of fading spread-spectrum signals, a first plurality ofdetected spread-spectrum signals and a first multiplicity of detectedfading spread-spectrum signals, respectively. The second plurality ofmatched filters 25, 35, 45, 55 detects from the plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals, a second plurality of detected spread-spectrum signals and asecond multiplicity of detected fading spread-spectrum signals,respectively. The third plurality of matched filters 26, 36, 46, 56detects from the plurality of spread-spectrum signals and themultiplicity of fading spread-spectrum signals, a third plurality ofdetected spread-spectrum signals and a third multiplicity of detectedfading spread-spectrum signals, respectively. The fourth plurality ofmatched filters 27, 37, 47, 57 detects from the plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals, a fourth plurality of detected spread-spectrum signals and afourth multiplicity of detected fading spread-spectrum signals,respectively.

The plurality of RAKE and space-diversity combiners combines eachplurality of detected spread-spectrum signals and each multiplicity ofdetected-fading spread-spectrum signals, respectively, from eachreceiver subsystem. This generates a plurality of combined signals. Moreparticularly, as depicted in FIG. 3, four RAKE and space-diversitycombiners are used, with each respective RAKE and space-diversitycombiner corresponding to a chip-sequence signal. A first RAKE andspace-diversity combiner 161 is coupled to the first matched filter 24,the fifth matched filter 25, the ninth matched filter 26, and thethirteenth matched filter 27, all of which have an impulse responsematched to the first chip-sequence signal. The plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals, which have a spread-spectrum subchannel defined by the firstchip-sequence signal, and detected by any or all of the first matchedfilter 24, the fifth matched filter 25, the ninth matched filter 26 andthe thirteenth matched filter 27, are combined by the first RAKE andspace-diversity combiner 161. At the output of the first RAKE andspace-diversity combiner 161 is a first combined signal. The first RAKEand space-diversity combiner 161 may use any of a number of techniquesfor combining signals, such as selecting the four strongest signals andadding their strengths, maximal ratio combining, maximal likelihoodcombining, etc. RAKE and combining techniques are well known in the art.

A second RAKE and space-diversity combiner 162 is coupled to the secondmatched filter 34, the sixth matched filter 35, the tenth matched filter36, and the fourteenth matched filter 37, all of which have an impulseresponse matched to the second chip-sequence signal. The plurality ofspread-spectrum signals and the multiplicity of fading spread-spectrumsignals, which have a spread-spectrum subchannel defined by the secondchip-sequence signal, and detected by any or all of the second matchedfilter 34, the sixth matched filter 35, the tenth matched filter 36 andthe fourteenth matched filter 37, are combined by the second RAKE andspace-diversity combiner 162. At the output of the second RAKE andspace-diversity combiner 162 is a second combined signal. The secondRAKE and space-diversity combiner 162 may use any of a number oftechniques for combining signals, such as selecting the four strongestsignals and adding their strengths, maximal ratio combining, maximallikelihood combining, etc. RAKE and combining techniques are well knownin the art.

A third RAKE and space-diversity combiner 163 is coupled to the thirdmatched filter 44, the seventh matched filter 45, the eleventh matchedfilter 46, and the fifteenth matched filter 47, all of which have animpulse response matched to the third chip-sequence signal. Theplurality of spread-spectrum signals and the multiplicity of fadingspread-spectrum signals, which have a spread-spectrum subchannel definedby the third chip-sequence signal, and detected by any or all of thethird matched filter 44, the seventh matched filter 45, the eleventhmatched filter 46 and the fifteenth matched filter 47, are combined bythe third RAKE and space-diversity combiner 163. At the output of thethird RAKE and space-diversity combiner 163 is a third combined signal.The third RAKE and space-diversity combiner 163 may use any of a numberof techniques for combining signals, such as selecting the fourstrongest signals and adding their strengths, maximal ratio combining,maximal likelihood combining, etc. RAKE and combining techniques arewell known in the art.

A fourth RAKE and space-diversity combiner 164 is coupled to the fourthmatched filter 54, the eighth matched filter 55, the twelfth matchedfilter 56, and the sixteenth matched filter 57, all of which have animpulse response matched to the fourth chip-sequence signal. Theplurality of spread-spectrum signals and the multiplicity of fadingspread-spectrum signals, which have a spread-spectrum subchannel definedby the fourth chip-sequence signal, and detected by any or all of thefourth matched filter 54, the eighth matched filter 55, the twelfthmatched filter 56 and the sixteenth matched filter 57, are combined bythe fourth RAKE and space-diversity combiner 164. At the output of thefourth RAKE and space-diversity combiner 164 is a fourth combinedsignal. The fourth RAKE and space-diversity combiner 164 may use any ofa number of techniques for combining signals, such as selecting the fourstrongest signals and adding their strengths, maximal ratio combining,maximal likelihood combining, etc. RAKE and combining techniques arewell known in the art.

The multiplexer 132 is coupled to the plurality of RAKE andspace-diversity combiners. As illustratively shown in FIG. 3, themultiplexer 132 is coupled to the first RAKE and space-diversitycombiner 161, to the second RAKE and space-diversity combiner 162, tothe third RAKE and space-diversity combiner 163, and to the fourth RAKEand space-diversity combiner 164. The multiplexer 132 multiplexes thefirst combined signal, the second combined signal, the third combinedsignal and the fourth combined signal, to generate a multiplexed signal.Thus, more generally, the multiplexer 132 multiplexes the plurality ofcombined signals to generate the multiplexed signal. The de-interleaver61 de-interleaves the multiplexed signal from the multiplexer 132 togenerate a de-interleaved signal, and the FEC decoder 62 decodes thede-interleaved signal to output the data. Buffer or memory circuits maybe inserted between the multiplexer 132 and de-interleaver 61, forstoring a plurality of multiplexed signals before the de-interleaver.Alternatively, the memory circuits may be incorporated as part of thede-interleaver.

In use, data are encoded by FEC encoder 21 as FEC data, and the FEC dataare interleaved by interleaver 22 generating interleaved data. Thedemultiplexer 32 demultiplexes the interleaved data into a plurality ofsubchannels and the plurality of spread-spectrum devices 23, 33, 43, 53spread-spectrum process the plurality of subchannels of data with aplurality of chip-sequence signals, respectively. The spread-spectrumprocessing generates a plurality of spread-spectrum-subchannel signals,respectively.

The plurality of transmit antennas radiate the plurality ofspread-spectrum-subchannel signals as a plurality of spread-spectrumsignals, respectively, over the communications channel.

At the receiver, a plurality of receiver antennas RA1, RA2, RA3, RA4receive the plurality of spread-spectrum signals and the multiplicity offading spread-spectrum signals. At each receiver antenna, and by way ofexample, the first receiver antenna RA1, there are a plurality ofmatched filters which detect the plurality of spread-spectrum signalsand the multiplicity of fading spread-spectrum signals, as a pluralityof detected spread-spectrum signals and a multiplicity ofdetected-fading spread-spectrum signals, respectively. The plurality ofRAKE and space-diversity combiners 161, 162, 163, 164 combine theplurality of detected spread-spectrum signals and the multiplicity ofdetected-fading spread-spectrum signals from each of the plurality ofreceiver subsystems, thereby generating a plurality of combined signals.

The multiplexer 132 multiplexes the plurality of combined signals as amultiplexed signal. The de-interleaver 61 de-interleaves the multiplexedsignal, and the FEC decoder 62 decodes the de-interleaved signal.

Since the symbol amplitudes are readily available, the presence of asmall or low level symbol amplitude, even after coding, is a goodindication of a processing error. Thus, erasure decoding is preferred inthis system to improve performance. During RAKE and space combining, thenoise level in each symbol also is measured. This is readily done in amatched filter by sampling the matched filter at a time, not being thesymbol sampling time. The noise level at each symbol is recorded orstored in memory, and any significant increase above a predefinedthreshold, such as 3 dB, is transmitted to the FEC decoder for erasuredecoding. Erasure decoding is well known in the art.

As an example of the performance improvement resulting from the presentinvention, consider that a single transmitter antenna and a singlereceiver antenna are employed in a system. Let the probability of beingshadowed be q. Then q represents the fractional outage time. The orderof combining is important if each transmitter antenna sends differentdata. If each transmitter antenna sent the same data, then the ordering,with appropriate delays, is not important.

Consider using a single transmitter antenna and M receiver antennas.Assuming independence, the probability of a blocked transmission isq^(M). Further, the multipath outputs at each receiver are combinedusing RAKE (time diversity), and then the resulting output at eachreceiver is combined (space diversity). In the antenna system, thetransmitted power, to each receiver antenna, is P_(T) and the processinggain is PG.

In the above example, assume independence, that is, the probability ofbeing blocked to a first receiver antenna, RA1, does not alter theprobability of being blocked to a second receiver antenna, RA2, forexample. In many cases, however, this assumption may not be correct. Alarge building may block a first receiver antenna, RA1, a secondreceiver antenna, RA2, and a third receiver antenna, RA3, from a user'stransmitter antenna. In such a situation it is often beneficial totransmit from several transmitting antennas. In a system employing Ntransmit antennas and M receiver antennas, the transmitted power fromeach transmitter antenna is reduced by N and the processing gain isincreased by N. However, the interference also is increased by N. Thus,there is no signal-to-noise ratio (SNR) improvement in a Gaussianchannel, and the advantage of such a system is increased access, i.e.,significantly less outage time in a fading channel, a considerationneeded for wireless system performance to approach that of a wiredsystem.

A space coding technique is shown in FIGS. 4, 5 and 6. Note that thedata are interleaved and FEC encoded using a rate R=½ code, such as aconvolutional code. The same data then is transmitted over all transmitantennas. In FIGS. 4 and 5, two transmit antennas are shown. In thissystem, after performing the RAKE operation, two receiver systemsperform a standard space diversity maximal-ratio-combining to optimizeperformance.

Assume that each transmission is received by all four receiver antennas.Then such receiver performs a RAKE reception for each transmitterantenna's signal. These signals are then combined using maximal ratiocombining for space diversity. The resulting output of each antenna canthen be combined. Of course, any order of combining yields the sameresult and all combining from all receiver antennas can be donesimultaneously (RAKE and space diversity). The order depends on systemimplementation and does not affect performance. Erasure decoding may beemployed at the FEC decoder.

The second embodiment of the antenna system is shown in FIGS. 4, 5 and6. In FIG. 4, the invention includes FEC encoder 21, coupled to theinterleaver 22. From the interleaver 22, the system includes at leastone delay device 181 and at least two spread-spectrum devices 23, 33.The system may include a plurality of delay devices, with each delaydevice having a delay different from other delay devices in theplurality of delay devices. The delay device 181 delays the interleaveddata going to the second spread-spectrum device 33. The firstspread-spectrum device 23 spread-spectrum processes the interleaved datawith the first chip-sequence signal from the chip-sequence generator 31,and the second spread-spectrum device 33 spread-spectrum processes thedelayed version of the interleaved data with the second chip-sequencesignal from chip-sequence sequence signal generator 31. The firsttransmitter antenna TA1 radiates the first spread-spectrum signal fromthe first spread-spectrum device 23, and the second transmitter antennaTA2 radiates the second spread-spectrum signal from the secondspread-spectrum device 33.

An alternative to FIG. 4 is shown in FIG. 5. Data are firstdemultiplexed by demultiplexer 32 into a first stream of data and asecond stream of data. The second stream of data is delayed by delaydevice 181 with respect to the first stream of data. The first stream ofdata is FEC encoded by first FEC encoder 521 and interleaved by firstinterleaver 622. The delayed second stream of data is FEC encoded bysecond FEC encoder 621 and interleaved by second interleaver 622.

The receiver has a multiplicity of receiver subsystems which include aplurality of receiver antennas. Each subsystem corresponding to areceiver antenna has a plurality of matched filters. As shown in FIG. 6,by way of example, a first receiver antenna RA1 and a second receiverantenna RA2 are shown. The first receiver antenna RA1 is coupled to afirst matched filter 24 and a second matched filter 34. The secondreceiver antenna RA2 is coupled to a fifth matched filter 25 and a sixthmatched filter 35. The RAKE and space-diversity combiner 60 combines theoutputs from the first matched filter 24, the second matched filter 34,the fifth matched filter 25, and the sixth matched filter 35 to form acombined signal. The de-interleaver 61 de-interleaves the combinedsignal, and the FEC decoder 62 decodes the de-interleaved signal.

As an alternative to the embodiments described in FIGS. 4–6, anidentical chip-sequence signal can be used for the plurality ofchip-sequence signals. In this alternative, only a single matched filterhaving an impulse response matched to the chip-sequence signal, isrequired. Each transmitted signal is delayed by at least one chip.

FIG. 7 is a block diagram of a receiver system having a plurality ofmatched filters 24, 25, 26, 34, 35, 36, 44, 45, 46, coupled to areceiver antenna. As with FIG. 3, the plurality of matched filters 24,25, 26, 34, 35, 36, 44, 45, 46 has a plurality of impulse responsesmatched to the plurality of chip-sequence signals, respectively. Theplurality of matched filters 24, 25, 26, 34, 35, 36, 44, 45, 46 detectsthe plurality of spread-spectrum signals and the multiplicity of fadingspread-spectrum signals, as a plurality of detected spread-spectrumsignals and a multiplicity of detected-fading spread-spectrum signals,respectively.

Also illustrated in FIG. 7 is a plurality of RAKE and space-diversitycombiners 761, 762, 763, coupled to the plurality of matched filters 24,25, 26, 34, 35, 36, 44, 45, 46, with a first RAKE and space-diversitycombiner 761 coupled to each matched filter 24, 25, 26 having an impulseresponse matched to a first chip-sequence signal, and with respectiveRAKE and space-diversity combiners coupled to respective matched filtershaving impulse responses matched to respective chip-sequence signals.The plurality of RAKE and space-diversity combiners 761, 762, 763combines, for a respective chip-sequence signal, the plurality ofdetected spread-spectrum signals and the multiplicity of detected-fadingspread-spectrum signals from the plurality of matched filters 24, 25,26, 34, 35, 36, 44, 45, 46. The combining generates a plurality ofcombined signals and a plurality of signal amplitudes, respectively. Afirst combined signal is from the first RAKE and space-diversitycombiner 761, and respective combined signals are from respective RAKEand space-diversity combiners.

A multiplexer 765 is coupled to the plurality of RAKE and spacediversity combiners 761, 762, 763. The multiplexer 765 multiplexes theplurality of combined signals, thereby generating a multiplexed signal.A de-interleaver 61 is coupled to the multiplexer 765 forde-interleaving the multiplexed signal from the multiplexer, therebygenerating a de-interleaved signal. The decoder is coupled to thede-interleaver. The decoder 62 decodes the de-interleaved signal.

It will be apparent to those skilled in the art that variousmodifications can be made to the efficient shadow reduction antennasystem for spread spectrum of the instant invention without departingfrom the scope or spirit of the invention, and it is intended that thepresent invention cover modifications and variations of the efficientshadow reduction antenna system for spread spectrum provided they comewithin the scope of the appended claims and their equivalents.

1. A multiple-input-multiple-output (MIMO) method for receiving datahaving symbols, with the data having symbols demultiplexed into aplurality of subchannels of data, with the plurality of subchannels ofdata spread-spectrum processed with a plurality of chip-sequencesignals, respectively, with each chip-sequence signal different fromother chip-sequence signals in the plurality of chip-sequence signals,thereby generating a plurality of spread-spectrum-subchannel signals,respectively, with the plurality of spread-spectrum-subchannel signalsradiated, using radio waves, from a plurality of antennas as a pluralityof spread-spectrum signals, respectively, with the plurality ofspread-spectrum signals passing through a communications channel havingmultipath, thereby generating, from the plurality of spread-spectrumsignals, at least a first spread-spectrum signal having a first channelof data arriving from a first path of the multipath, and a secondspread-spectrum signal having a second channel of data arriving from asecond path of the multipath, comprising the steps of: receiving thefirst spread-spectrum signal and the second spread-spectrum signal witha plurality of receiver antennas; detecting, at each receiver antenna ofthe plurality of receiver antennas, the first spread-spectrum signal asa first plurality of detected spread-spectrum signals, respectively;detecting, at each receiver antenna of the plurality of receiverantennas, the second spread-spectrum signal as a second plurality ofdetected spread-spectrum signals, respectively; combining, from eachreceiver antenna of the plurality of receiver antennas, each of thefirst plurality of detected spread-spectrum signals, thereby generatinga first combined signal; and combining, from each receiver antenna ofthe plurality of receiver antennas, each of the second plurality ofdetected spread-spectrum signals, thereby generating a second combinedsignal.
 2. The MIMO method as set forth in claim 1, further comprisingthe step of multiplexing the first combined signal with the secondcombined signal, thereby generating a multiplexed signal.
 3. The MIMOmethod, as set forth in claim 1, for receiving data having symbols, fromthe communications channel having multipath, thereby generating, fromthe plurality of spread-spectrum signals, a third spread-spectrum signalhaving a third channel of data arriving from any of the first path, thesecond path, or a third path of the multipath, further comprising thesteps of: receiving the third spread-spectrum signal with the pluralityof receiver antennas; detecting, at each receiver antenna of theplurality of receiver antennas, the third spread-spectrum signal, as athird plurality of detected spread-spectrum signals; and combining, fromeach receiver antenna of the plurality of receiver antennas, each of thethird plurality of detected spread-spectrum signals, thereby generatinga third combined signal.
 4. The MIMO method as set forth in claim 3,further comprising the step of multiplexing the first combined signal,the second combined signal, and the third combined signal, therebygenerating a multiplexed signal.
 5. The MIMO method, as set forth inclaim 3, for receiving data having symbols, from the communicationschannel having multipath, thereby generating, from the plurality ofspread-spectrum signals, a fourth spread-spectrum signal having a fourthchannel of data arriving from any of the first path, the second path,the third path, or a fourth path of the multipath, further comprisingthe steps of: receiving the fourth spread-spectrum signal with theplurality of receiver antennas; detecting, at each receiver antenna ofthe plurality of receiver antennas, the fourth spread-spectrum signal,as a fourth plurality of detected spread-spectrum signals; andcombining, from each receiver antenna of the plurality of receiverantennas, each of the fourth plurality of detected spread-spectrumsignals, thereby generating a fourth combined signal.
 6. The MIMO methodas set forth in claim 5, further comprising the step of multiplexing thefirst combined signal, the second combined signal, the third combinedsignal, and the fourth combined signal, thereby generating a multiplexedsignal.
 7. The MIMO method, as set forth in claim 5, for receiving datahaving symbols, from the communications channel having multipath,thereby generating, from the plurality of spread-spectrum signals, afifth spread-spectrum signal having a fifth channel of data arrivingfrom any of the first path, the second path, the third path of themultipath, the fourth path, or a fifth path, further comprising thesteps of: receiving the fifth spread-spectrum signal with the pluralityof receiver antennas; detecting, at each receiver antenna of theplurality of receiver antennas, the fifth spread-spectrum signal, as afifth plurality of detected spread-spectrum signals; and combining, fromeach receiver antenna of the plurality of receiver antennas, each of thefifth plurality of detected spread-spectrum signals, thereby generatinga fifth combined signal.
 8. The MIMO method as set forth in claim 7,further comprising the step of multiplexing the first combined signal,the second combined signal, the third combined signal, the fourthcombined signal, and the fifth combined signal, thereby generating amultiplexed signal.
 9. A multiple-input-multiple-output (MIMO) systemfor receiving data having symbols, with the data having symbolsdemultiplexed into a plurality of subchannels of data, with theplurality of subchannels of data spread-spectrum processed with aplurality of chip-sequence signals, respectively, with eachchip-sequence signal different from other chip-sequence signals in theplurality of chip-sequence signals, thereby generating a plurality ofspread-spectrum-subchannel signals, respectively, with the plurality ofspread-spectrum-subchannel signals radiated, using radio waves, from aplurality of antennas as a plurality of spread-spectrum signals,respectively, with the plurality of spread-spectrum signals passingthrough a communications channel having multipath, thereby generating,from the plurality of spread-spectrum signals, at least a firstspread-spectrum signal having a first channel of data arriving from afirst path of the multipath, and a second spread-spectrum signal havinga second channel of data arriving from a second path of the multipath,comprising: a plurality of receiver antennas for receiving the firstspread-spectrum signal and the second spread-spectrum signal; aplurality of despreading devices for detecting, at each receiver antennaof the plurality of receiver antennas, the first spread-spectrum signaland the second spread-spectrum signal, as a first plurality of detectedspread-spectrum signals and a second plurality of detectedspread-spectrum signals, respectively; and a plurality of combiners forcombining, from each receiver antenna of the plurality of receiverantennas, each of the first plurality of detected spread-spectrumsignals, thereby generating a first combined signal, and for combining,from each receiver antenna of the plurality of receiver antennas, eachof the second plurality of detected spread-spectrum signals, therebygenerating a second combined signal.
 10. The MIMO system as set forth inclaim 9, further comprising a multiplexer for multiplexing the firstcombined signal with the second combined signal, thereby generating amultiplexed signal.
 11. The MIMO system as set forth in claim 9, forreceiving data having symbols, from the communications channel havingmultipath, thereby generating, from the plurality of spread-spectrumsignals, a third spread-spectrum signal having a third channel of dataarriving from any of the first path, the second path, or a third path ofthe multipath, further comprising: said plurality of receiver antennasfor receiving the third spread-spectrum signal; said plurality ofdespreading devices for detecting, at each receiver antenna of theplurality of receiver antennas, the third spread-spectrum signal, as athird plurality of detected spread-spectrum signals; and said pluralityof combiners for combining, from each receiver antenna of the pluralityof receiver antennas, each of the third plurality of detectedspread-spectrum signals, thereby generating a third combined signal. 12.The MIMO system as set forth in claim 11, further comprising amultiplexer for multiplexing the first combined signal, the secondcombined signal, and the third combined signal, thereby generating amultiplexed signal.
 13. The MIMO system, as set forth in claim 11, forreceiving data having symbols, from the communications channel havingmultipath, thereby generating, from the plurality of spread-spectrumsignals, a fourth spread-spectrum signal having a fourth channel of dataarriving from any of the first path, the second path, the third path, ora fourth path of the multipath, further comprising: said plurality ofreceiver antennas for receiving the fourth spread-spectrum signal; saidplurality of despreading devices for detecting, at each receiver antennaof the plurality of receiver antennas, the fourth spread-spectrumsignal, as a fourth plurality of detected spread-spectrum signals; andsaid plurality of combiners for combining, from each receiver antenna ofthe plurality of receiver antennas, each of the fourth plurality ofdetected spread-spectrum signals, thereby generating a fourth combinedsignal.
 14. The MIMO system as set forth in claim 13, further comprisinga multiplexer for multiplexing the first combined signal, the secondcombined signal, the third combined signal, and the fourth combinedsignal, thereby generating a multiplexed signal.
 15. The MIMO system, asset forth in claim 13, for receiving data having symbols, from thecommunications channel having multipath, thereby generating, from theplurality of spread-spectrum signals, a fifth spread-spectrum signalhaving a fifth channel of data arriving from any of the first path, thesecond path, or the third path of the multipath, the fourth path, or afifth path, further comprising: said plurality of receiver antennas forreceiving the fifth spread-spectrum signal; said plurality ofspread-spectrum detectors for detecting, at each receiver antenna of theplurality of receiver antennas, the fifth spread-spectrum signal, as afifth plurality of detected spread-spectrum signals; and said pluralityof combiners for combining, from each receiver antenna of the pluralityof receiver antennas, each of the fifth plurality of detectedspread-spectrum signals, thereby generating a fifth combined signal. 16.The MIMO system set forth in claim 15, further comprising a multiplexerfor multiplexing the first combined signal, the second combined signal,the third combined signal, the fourth combined signal, and the fifthcombined signal, thereby generating a multiplexed signal.
 17. A MIMOsystem for receiving data having symbols, with the data having symbolsdemultiplexed into a plurality of subchannels of data, with theplurality of subchannels of data spread-spectrum processed with aplurality of chip-sequence signals, respectively, with eachchip-sequence signal different from other chip-sequence signals in theplurality of chip-sequence signals, thereby generating a plurality ofspread-spectrum-subchannel signals, respectively, with the plurality ofspread-spectrum-subchannel signals radiated, using radio waves, from aplurality of antennas as a plurality of spread-spectrum signals,respectively, with the plurality of spread-spectrum signals passingthrough a communications channel having multipath, thereby generating,from the plurality of spread-spectrum signals, at least a firstspread-spectrum signal having a first channel of data arriving from afirst path of the multipath, and a second spread-spectrum signal havinga second channel of data arriving from a second path of the multipath,comprising: receiver-antenna means for receiving the firstspread-spectrum signal and the second spread-spectrum signal;despreading means, coupled to said receiver-antenna means, fordetecting, at each receiver antenna of the plurality of receiverantennas, the first spread-spectrum signal and the secondspread-spectrum signal, as a first plurality of detected spread-spectrumsignals and a second plurality of detected spread-spectrum signals,respectively; and combiner means, coupled to said despreading means, forcombining, from each receiver antenna of the plurality of receiverantennas, each of the first plurality of detected spread-spectrumsignals, thereby generating a first combined signal, and for combining,from each receiver antenna of the plurality of receiver antennas, eachof the second plurality of detected spread-spectrum signals, therebygenerating a second combined signal.
 18. The MIMO system as set forth inclaim 17, further comprising multiplexer means for multiplexing thefirst combined signal with the second combined signal, therebygenerating a multiplexed signal.
 19. The MIMO system as set forth inclaim 17, for receiving data having symbols, from the communicationschannel having multipath, thereby generating, from the plurality ofspread-spectrum signals, a third spread-spectrum signal having a thirdchannel of data arriving from any of the first path, the second path, ora third path of the multipath, further comprising: said receiver-antennameans for receiving the third spread-spectrum signal; said despreadingmeans for detecting, at each receiver antenna of the plurality ofreceiver antennas, the third spread-spectrum signal, as a thirdplurality of detected spread-spectrum signals; and said combiner meansfor combining, from each receiver antenna of the plurality of receiverantennas, each of the third plurality of detected spread-spectrumsignals, thereby generating a third combined signal.
 20. The MIMO methodas set forth in claim 19, further comprising multiplexer means formultiplexing the first combined signal, the second combined signal, andthe third combined signal, thereby generating a multiplexed signal. 21.The MIMO system, as set forth in claim 19, for receiving data havingsymbols, from the communications channel having multipath, therebygenerating, from the plurality of spread-spectrum signals, a fourthspread-spectrum signal having a fourth channel of data arriving from anyof the first path, the second path, the third path, or a fourth path ofthe multipath, further comprising: said receiver-antenna means forreceiving the fourth spread-spectrum signal; said despreading means fordetecting, at each receiver antenna of the plurality of receiverantennas, the fourth spread-spectrum signal, as a fourth plurality ofdetected spread-spectrum signals; and said combiner means for combining,from each receiver antenna of the plurality of receiver antennas, eachof the fourth plurality of detected spread-spectrum signals, therebygenerating a fourth combined signal.
 22. The MIMO system as set forth inclaim 21, further comprising multiplexer means for multiplexing thefirst combined signal, the second combined signal, the third combinedsignal, and the fourth combined signal, thereby generating a multiplexedsignal.
 23. The MIMO system, as set forth in claim 21, for receivingdata having symbols, from the communications channel having multipath,thereby generating, from the plurality of spread-spectrum signals, afifth spread-spectrum signal having a fifth channel of data arrivingfrom any of the first path, the second path, or the third path of themultipath, the fourth path, or a fifth path, further comprising: saidreceiver-antenna means for receiving the fifth spread-spectrum signal;said despreading means for detecting, at each receiver antenna of theplurality of receiver antennas, the fifth spread-spectrum signal, as afifth plurality detected spread-spectrum signals; and said combinermeans for combining, from each receiver antenna of the plurality ofreceiver antennas, each of the fifth plurality of detectedspread-spectrum signals, thereby generating a fifth combined signal. 24.The MIMO system as set forth in claim 23, further comprising multiplexermeans for multiplexing the first combined signal, the second combinedsignal, the third combined signal, the fourth combined signal, and thefifth combined signal, thereby generating a multiplexed signal.
 25. Amultiple input multiple output (MIMO) method improvement, fortransmitting data having symbols, over a communications channel,comprising the steps of: demultiplexing the data into a plurality ofsubchannels of data; spread-spectrum processing the plurality ofsubchannels of data, with the plurality of subchannels of dataspread-spectrum processed with a plurality of chip-sequence signals,respectively, with each chip-sequence signal different from otherchip-sequence signals in the plurality of chip-sequence signals, therebygenerating a plurality of spread-spectrum-subchannel signals,respectively; radiating from a plurality of antennas, using radio waves,the plurality of spread-spectrum-subchannel signals, over thecommunications channel, as a plurality of spread-spectrum signals,respectively; imparting, from the communications channel, multipath onthe plurality of spread-spectrum signals, thereby generating at least afirst spread-spectrum signal having a first channel of data arrivingfrom a first path of the multipath, and a second spread-spectrum signalhaving a second channel of data arriving from a second path of themultipath; receiving the first spread-spectrum signal and the secondspread-spectrum signal with a plurality of receiver antennas; detecting,at each receiver antenna of the plurality of receiver antennas, thefirst spread-spectrum signal and the second spread-spectrum signal, as afirst plurality of detected spread-spectrum signals and a secondplurality of detected spread-spectrum signals, respectively; combining,from each receiver antenna of the plurality of receiver antennas, eachof the first plurality of detected spread-spectrum signals, therebygenerating a first combined signal; and combining, from each receiverantenna of the plurality of receiver antennas, each of the secondplurality of detected spread-spectrum signals, thereby generating asecond combined signal.
 26. The MIMO method as set forth in claim 25,further comprising the step of multiplexing the first combined signalwith the second combined signal, thereby generating a multiplexedsignal.
 27. The MIMO method, as set forth in claim 25, for receivingdata having symbols, from the communications channel having multipath,thereby generating, from the plurality of spread-spectrum signals, witha third spread-spectrum signal having a third channel of data arrivingfrom any of the first path, the second path, or a third path of themultipath, further comprising the steps of: receiving the thirdspread-spectrum signal with the plurality of receiver antennas;detecting, at each receiver antenna of the plurality of receiverantennas, the third spread-spectrum signal, as a third plurality ofdetected spread-spectrum signals; and combining, from each receiverantenna of the plurality of receiver antennas, each of the thirdplurality of detected spread-spectrum signals, thereby generating athird combined signal.
 28. The MIMO method as set forth in claim 27,further comprising the step of multiplexing the first combined signal,the second combined signal, and the third combined signal, therebygenerating a multiplexed signal.
 29. The MIMO method, as set forth inclaim 27, for receiving data having symbols, from the communicationschannel having multipath, thereby generating, from the plurality ofspread-spectrum signals, with a fourth spread-spectrum signal having afourth channel of data arriving from any of the first path, the secondpath, the third path, or a fourth path of the multipath, furthercomprising the steps of: receiving the fourth spread-spectrum signalwith the plurality of receiver antennas; detecting, at each receiverantenna of the plurality of receiver antennas, the fourthspread-spectrum signal, as a fourth plurality of detectedspread-spectrum signals; and combining, from each receiver antenna ofthe plurality of receiver antennas, each of the fourth plurality ofdetected spread-spectrum signals, thereby generating a fourth combinedsignal.
 30. The MIMO method as set forth in claim 29, further comprisingthe step of multiplexing the first combined signal, the second combinedsignal, the third combined signal, and the fourth combined signal,thereby generating a multiplexed signal.
 31. The MIMO method, as setforth in claim 29, for receiving data having symbols, from thecommunications channel having multipath, thereby generating, from theplurality of spread-spectrum signals, a fifth spread-spectrum signalhaving a fifth channel of data arriving from any of the first path, thesecond path, the third path of the multipath, the fourth path, or afifth path, further comprising the steps of: receiving the fifthspread-spectrum signal with the plurality of receiver antennas;detecting, at each receiver antenna of the plurality of receiverantennas, the fifth spread-spectrum signal, as a fifth plurality ofdetected spread-spectrum signals; and combining, from each receiverantenna of the plurality of receiver antennas, each of the fifthplurality of detected spread-spectrum signals, thereby generating afifth combined signal.
 32. The MIMO method as set forth in claim 31,further comprising the step of multiplexing the first combined signal,the second combined signal, the third combined signal, the fourthcombined signal, and the fifth combined signal, thereby generating amultiplexed signal.
 33. A multiple input multiple output (MIMO) system,for transmitting data having symbols, over a communications channel,comprising: a demultiplexer for demultiplexing the data into a pluralityof subchannels of data; a plurality of spread-spectrum devices forspread-spectrum processing the plurality of subchannels of data, withthe plurality of subchannels of data spread-spectrum processed with aplurality of chip-sequence signals, respectively, with eachchip-sequence signal different from other chip-sequence signals in theplurality of chip-sequence signals, thereby generating a plurality ofspread-spectrum-subchannel signals, respectively; a plurality oftransmitter antennas for radiating, using radio waves, the plurality ofspread-spectrum-subchannel signals, over the communications channel, asa plurality of spread-spectrum signals, respectively; saidcommunications channel for imparting multipath on the plurality ofspread-spectrum signals, thereby generating at least a firstspread-spectrum signal having a first channel of data arriving from afirst path of the multipath, and a second spread-spectrum signal havinga second channel of data arriving from a second path of the multipath; aplurality of receiver antennas for receiving the first spread-spectrumsignal and the second spread-spectrum signal; a plurality of despreadingdevices for detecting, at each receiver antenna of the plurality ofreceiver antennas, the first spread-spectrum signal and the secondspread-spectrum signal, as a first plurality of detected spread-spectrumsignals and a second plurality of detected spread-spectrum signals,respectively; and a plurality of combiners for combining, from eachreceiver antenna of the plurality of receiver antennas, each of thefirst plurality of detected spread-spectrum signals, thereby generatinga first combined signal, and for combining, from each receiver antennaof the plurality of receiver antennas, each of the second plurality ofdetected spread-spectrum signals, thereby generating a second combinedsignal.
 34. The MIMO system as set forth in claim 33, further comprisinga multiplexer for multiplexing the first combined signal with the secondcombined signal, thereby generating a multiplexed signal.
 35. The MIMOsystem as set forth in claim 33, for receiving data having symbols, fromthe communications channel having multipath, thereby generating, fromthe plurality of spread-spectrum signals, a third spread-spectrum signalhaving a third channel of data arriving from any of the first path, thesecond path, or a third path of the multipath, further comprising: saidplurality of receiver antennas for receiving the third spread-spectrumsignal; said plurality of despreading devices for detecting, at eachreceiver antenna of the plurality of receiver antennas, the thirdspread-spectrum signal, as a third plurality of detected spread-spectrumsignals; and said plurality of combiners for combining, from eachreceiver antenna of the plurality of receiver antennas, each of thethird plurality of detected spread-spectrum signals, thereby generatinga third combined signal.
 36. The MIMO system as set forth in claim 35,further comprising a multiplexer for multiplexing the first combinedsignal, the second combined signal, and the third combined signal,thereby generating a multiplexed signal.
 37. The MIMO system, as setforth in claim 35, for receiving data having symbols, from thecommunications channel having multipath, thereby generating, from theplurality of spread-spectrum signals, a fourth spread-spectrum signalhaving a fourth channel of data arriving from any of the first path, thesecond path, the third path, or a fourth path of the multipath, furthercomprising: said plurality of receiver antennas for receiving the fourthspread-spectrum signal; said plurality of despreading devices fordetecting, at each receiver antenna of the plurality of receiverantennas, the fourth spread-spectrum signal, as a fourth plurality ofdetected spread-spectrum signals; and said plurality of combiners forcombining, from each receiver antenna of the plurality of receiverantennas, each of the fourth plurality of detected spread-spectrumsignals, thereby generating a fourth combined signal.
 38. The MIMOsystem as set forth in claim 37, further comprising a multiplexer formultiplexing the first combined signal, the second combined signal, thethird combined signal, and the fourth combined signal, therebygenerating a multiplexed signal.
 39. The MIMO system, as set forth inclaim 37, for receiving data having symbols, from the communicationschannel having multipath, thereby generating, from the plurality ofspread-spectrum signals, a fifth spread-spectrum signal having a fifthchannel of data arriving from any of the first path, the second path, orthe third path of the multipath, the fourth path, or a fifth path,further comprising: said plurality of receiver antennas for receivingthe fifth spread-spectrum signal; said plurality of spread-spectrumdetectors for detecting, at each receiver antenna of the plurality ofreceiver antennas, the fifth spread-spectrum signal, as a fifthplurality of detected spread-spectrum signals; and said plurality ofcombiners for combining, from each receiver antenna of the plurality ofreceiver antennas, each of the fifth plurality of detectedspread-spectrum signals, thereby generating a fifth combined signal. 40.The MIMO system set forth in claim 39, further comprising a multiplexerfor multiplexing the first combined signal, the second combined signal,the third combined signal, the fourth combined signal, and the fifthcombined signal, thereby generating a multiplexed signal.
 41. A multipleinput multiple output (MIMO) system, for transmitting data havingsymbols, over a communications channel, comprising: demultiplexer meansfor demultiplexing the data into a plurality of subchannels of data;spread-spectrum processing means for spread-spectrum processing theplurality of subchannels of data, with the plurality of subchannels ofdata spread-spectrum processed with a plurality of chip-sequencesignals, respectively, with each chip-sequence signal different fromother chip-sequence signals in the plurality of chip-sequence signals,thereby generating a plurality of spread-spectrum-subchannel signals,respectively; a plurality of transmitter-antenna means for radiating,using radio waves, the plurality of spread-spectrum-subchannel signals,over the communications channel, as a plurality of spread-spectrumsignals, respectively; said communications channel for impartingmultipath on the plurality of spread-spectrum signals, therebygenerating at least a first spread-spectrum signal having a firstchannel of data arriving from a first path of the multipath, and asecond spread-spectrum signal having a second channel of data arrivingfrom a second path of the multipath; receiver-antenna means forreceiving the first spread-spectrum signal and the secondspread-spectrum signal; despreading means, coupled to saidreceiver-antenna means, for detecting, at each receiver antenna of theplurality of receiver antennas, the first spread-spectrum signal and thesecond spread-spectrum signal, as a first plurality of detectedspread-spectrum signals and a second plurality of detectedspread-spectrum signals, respectively; and combiner means, coupled tosaid despreading means, for combining, from each receiver antenna of theplurality of receiver antennas, each of the first plurality of detectedspread-spectrum signals, thereby generating a first combined signal, andfor combining, from each receiver antenna of the plurality of receiverantennas, each of the second plurality of detected spread-spectrumsignals, thereby generating a second combined signal.
 42. The MIMOsystem as set forth in claim 41, further comprising multiplexer meansfor multiplexing the first combined signal with the second combinedsignal, thereby generating a multiplexed signal.
 43. The MIMO system asset forth in claim 41, for receiving data having symbols, from thecommunications channel having multipath, thereby generating, from theplurality of spread-spectrum signals, a third spread-spectrum signalhaving a third channel of data arriving from any of the first path, thesecond path, or a third path of the multipath, further comprising: saidreceiver-antenna means for receiving the third spread-spectrum signal;said despreading means for detecting, at each receiver antenna of theplurality of receiver antennas, the third spread-spectrum signal, as athird plurality of detected spread-spectrum signals; and said combinermeans for combining, from each receiver antenna of the plurality ofreceiver antennas, each of the third plurality of detectedspread-spectrum signals, thereby generating a third combined signal. 44.The MIMO system as set forth in claim 43, further comprising multiplexermeans for multiplexing the first combined signal, the second combinedsignal, and the third combined signal, thereby generating a multiplexedsignal.
 45. The MIMO system, as set forth in claim 43, for receivingdata having symbols, from the communications channel having multipath,thereby generating, from the plurality of spread-spectrum signals, afourth spread-spectrum signal having a fourth channel of data arrivingfrom any of the first path, the second path, the third path, or a fourthpath of the multipath, further comprising: said receiver-antenna meansfor receiving the fourth spread-spectrum signal; said despreading meansfor detecting, at each receiver antenna of the plurality of receiverantennas, the fourth spread-spectrum signal, as a fourth plurality ofdetected spread-spectrum signals; and said combiner means for combining,from each receiver antenna of the plurality of receiver antennas, eachof the fourth plurality of detected spread-spectrum signals, therebygenerating a fourth combined signal.
 46. The MIMO system as set forth inclaim 45, further comprising multiplexer means for multiplexing thefirst combined signal, the second combined signal, the third combinedsignal, and the fourth combined signal, thereby generating a multiplexedsignal.
 47. The MIMO system, as set forth in claim 45, for receivingdata having symbols, from the communications channel having multipath,thereby generating, from the plurality of spread-spectrum signals, afifth spread-spectrum signal having a fifth channel of data arrivingfrom any of the first path, the second path, or the third path of themultipath, the fourth path, or a fifth path, further comprising: saidreceiver-antenna means for receiving the fifth spread-spectrum signal;said despreading means for detecting, at each receiver antenna of theplurality of receiver antennas, the fifth spread-spectrum signal, as afifth plurality detected spread-spectrum signals; and said combinermeans for combining, from each receiver antenna of the plurality ofreceiver antennas, each of the fifth plurality of detectedspread-spectrum signals, thereby generating a fifth combined signal. 48.The MIMO system as set forth in claim 47, further comprising multiplexermeans for multiplexing the first combined signal, the second combinedsignal, the third combined signal, the fourth combined signal, and thefifth combined signal, thereby generating a multiplexed signal.
 49. TheMIMO method as set forth in claim 1 with the step of detecting the firstspread-spectrum signal and the second spread-spectrum signal, includingthe step of detecting, responsive to a first chip-sequence signal and toa second chip-sequence signal, the first spread-spectrum signal and thesecond spread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 50. The MIMO method as set forthin claim 3 with the step of detecting the third spread-spectrum signal,including the step of detecting, responsive to a third chip-sequencesignal, the third spread-spectrum signal as the third plurality ofdetected spread-spectrum signals, respectively.
 51. The MIMO method asset forth in claim 5 with the step of detecting the fourthspread-spectrum signal, including the step of detecting, responsive to afourth chip-sequence signal, the fourth spread-spectrum signal as thefourth plurality of detected spread-spectrum signals, respectively. 52.The MIMO method as set forth in claim 7 with the step of detecting thefifth spread-spectrum signal, including the step of detecting,responsive to a fifth chip-sequence signal, the fifth spread-spectrumsignal as the fifth plurality of detected spread-spectrum signals,respectively.
 53. The MIMO system as set forth in claim 9 with saidplurality of despreading devices, responsive to a first chip-sequencesignal and to a second chip-sequence signal, for detecting the firstspread-spectrum signal and the second spread-spectrum signal as thefirst plurality of detected spread-spectrum signals and the secondplurality of detected spread-spectrum signals, respectively.
 54. TheMIMO method as set forth in claim 11 with said plurality of despreadingdevices, responsive to a third chip-sequence signal, for detecting thethird spread-spectrum signal as the third plurality of detectedspread-spectrum signals, respectively.
 55. The MIMO system as set forthin claim 13 with said plurality of despreading devices, responsive to afourth chip-sequence signal, for detecting the fourth spread-spectrumsignal as the fourth plurality of detected spread-spectrum signals,respectively.
 56. The MIMO system as set forth in claim 15 with saidplurality of despreading devices, responsive to a fifth chip-sequencesignal, for detecting the fifth spread-spectrum signal as the fifthplurality of detected spread-spectrum signals, respectively.
 57. TheMIMO system as set forth in claim 17 with said despreading means,responsive to a first chip-sequence signal and to a second chip-sequencesignal, for detecting the first spread-spectrum signal and the secondspread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 58. The MIMO system as set forthin claim 19 with said despreading means, responsive to a thirdchip-sequence signal, for detecting the third spread-spectrum signal asthe third plurality of detected spread-spectrum signals, respectively.59. The MIMO system as set forth in claim 21 with said despreadingmeans, responsive to a fourth chip-sequence signal, for detecting thefourth spread-spectrum signal as the fourth plurality of detectedspread-spectrum signals, respectively.
 60. The MIMO system as set forthin claim 23 with said despreading means, responsive to a fifthchip-sequence signal, for detecting the fifth spread-spectrum signal asthe fifth plurality of detected spread-spectrum signals, respectively.61. The MIMO method as set forth in claim 25 with the step of detectingthe first spread-spectrum signal and the second spread-spectrum signal,including the step of detecting, responsive to a first chip-sequencesignal and to a second chip-sequence signal, the first spread-spectrumsignal and the second spread-spectrum signal as the first plurality ofdetected spread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 62. The MIMO method as set forthin claim 27 with the step of detecting the third spread-spectrum signal,including the step of detecting, responsive to a third chip-sequencesignal, the third spread-spectrum signal as the third plurality ofdetected spread-spectrum signals, respectively.
 63. The MIMO method asset forth in claim 29 with the step of detecting the fourthspread-spectrum signal, including the step of detecting, responsive to afourth chip-sequence signal, the fourth spread-spectrum signal as thefourth plurality of detected spread-spectrum signals, respectively. 64.The MIMO method as set forth in claim 31 with the step of detecting thefifth spread-spectrum signal, including the step of detecting,responsive to a fifth chip-sequence signal, the fifth spread-spectrumsignal as the fifth plurality of detected spread-spectrum signals,respectively.
 65. The MIMO system as set forth in claim 33 with saidplurality of despreading devices, responsive to a first chip-sequencesignal and to a second chip-sequence signal, for detecting the firstspread-spectrum signal and the second spread-spectrum signal as thefirst plurality of detected spread-spectrum signals and the secondplurality of detected spread-spectrum signals, respectively.
 66. TheMIMO system as set forth in claim 35 with said plurality of despreadingdevices, responsive to a third chip-sequence signal, for detecting thethird spread-spectrum signal as the third plurality of detectedspread-spectrum signals, respectively.
 67. The MIMO system as set forthin claim 37 with said plurality of despreading devices, responsive to afourth chip-sequence signal, for detecting the fourth spread-spectrumsignal as the fourth plurality of detected spread-spectrum signals,respectively.
 68. The MIMO system as set forth in claim 39 with saidplurality of despreading devices, responsive to a fifth chip-sequencesignal, for detecting the fifth spread-spectrum signal as the fifthplurality of detected spread-spectrum signals, respectively.
 69. TheMIMO system as set forth in claim 41 with said despreading means,responsive to a first chip-sequence signal and to a second chip-sequencesignal, for detecting the first spread-spectrum signal and the secondspread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 70. The MIMO system as set forthin claim 42 with said despreading means, responsive to a thirdchip-sequence signal, for detecting the third spread-spectrum signal asthe third plurality of detected spread-spectrum signals, respectively.71. The MIMO system as set forth in claim 43 with said despreadingmeans, responsive to a fourth chip-sequence signal, for detecting thefourth spread-spectrum signal as the fourth plurality of detectedspread-spectrum signals, respectively.
 72. The MIMO system as set forthin claim 44 with said despreading means, responsive to a fifthchip-sequence signal, for detecting the fifth spread-spectrum signal asthe fifth plurality of detected spread-spectrum signals, respectively.73. The MIMO method as set forth in claim 1 with the step of detectingthe first spread-spectrum signal and the second spread-spectrum signal,including the step of detecting, using a first filter matched to a firstchip-sequence signal and a second filter matched to a secondchip-sequence signal, the first spread-spectrum signal and the secondspread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 74. The MIMO method as set forthin claim 3 with the step of detecting the third spread-spectrum signal,including the step of detecting, using a third filter matched to a thirdchip-sequence signal, the third spread-spectrum signal as the thirdplurality of detected spread-spectrum signals, respectively.
 75. TheMIMO method as set forth in claim 5 with the step of detecting thefourth spread-spectrum signal, including the step of detecting, using afourth filter matched to a fourth chip-sequence signal, the fourthspread-spectrum signal as the fourth plurality of detectedspread-spectrum signals, respectively.
 76. The MIMO method as set forthin claim 7 with the step of detecting the fifth spread-spectrum signal,including the step of detecting, using a fifth filter matched to a fifthchip-sequence signal, the fifth spread-spectrum signal as the fifthplurality of detected spread-spectrum signals, respectively.
 77. TheMIMO system as set forth in claim 9 with said plurality of despreadingdevices including a first filter matched to a first chip-sequence signaland a second filter matched to a second chip-sequence signal, fordetecting the first spread-spectrum signal and the secondspread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 78. The MIMO system as set forthin claim 13 with said plurality of despreading devices including a thirdfilter matched to a third chip-sequence signal, for detecting the thirdspread-spectrum signal as the third plurality of detectedspread-spectrum signals, respectively.
 79. The MIMO system as set forthin claim 13 with said plurality of despreading devices including afourth filter matched to a fourth chip-sequence signal, for detectingthe fourth spread-spectrum signal as the fourth plurality of detectedspread-spectrum signals, respectively.
 80. The MIMO system as set forthin claim 15 with said plurality of despreading devices including a fifthfilter matched to a fifth chip-sequence signal, for detecting the fifthspread-spectrum signal as the fifth plurality of detectedspread-spectrum signals, respectively.
 81. The MIMO system as set forthin claim 17 with said despreading means including a first filter matchedto a first chip-sequence signal and a second filter matched to a secondchip-sequence signal, for detecting the first spread-spectrum signal andthe second spread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 82. The MIMO system as set forthin claim 19 with said despreading means including a third filter matchedto a third chip-sequence signal, for detecting the third spread-spectrumsignal as the third plurality of detected spread-spectrum signals,respectively.
 83. The MIMO system as set forth in claim 21 with saiddespreading means including a fourth filter matched to a fourthchip-sequence signal, for detecting the fourth spread-spectrum signal asthe fourth plurality of detected spread-spectrum signals, respectively.84. The MIMO system as set forth in claim 23 with said despreading meansincluding a fifth filter matched to a fifth chip-sequence signal, fordetecting the fifth spread-spectrum signal as the fifth plurality ofdetected spread-spectrum signals, respectively.
 85. The MIMO method asset forth in claim 25 with the step of detecting the firstspread-spectrum signal and the second spread-spectrum signal, includingthe step of detecting, using a first filter matched to a firstchip-sequence signal and a second filter matched to a secondchip-sequence signal, the first spread-spectrum signal and the secondspread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 86. The MIMO method as set forthin claim 27 with the step of detecting the third spread-spectrum signal,including the step of detecting, using a third filter matched to a thirdchip-sequence signal, the third spread-spectrum signal as the thirdplurality of detected spread-spectrum signals, respectively.
 87. TheMIMO method as set forth in claim 29 with the step of detecting thefourth spread-spectrum signal, including the step of detecting, using afourth filter matched to a fourth chip-sequence signal, the fourthspread-spectrum signal as the fourth plurality of detectedspread-spectrum signals, respectively.
 88. The MIMO method as set forthin claim 31 with the step of detecting the fifth spread-spectrum signal,including the step of detecting, using a fifth filter matched to a fifthchip-sequence signal, the fifth spread-spectrum signal as the fifthplurality of detected spread-spectrum signals, respectively.
 89. TheMIMO system as set forth in claim 33 with said plurality of despreadingdevices including a first filter matched to a first chip-sequence signaland a second filter matched to a second chip-sequence signal, fordetecting the first spread-spectrum signal and the secondspread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 90. The MIMO system as set forthin claim 35 with said plurality of despreading devices, including athird filter matched to a third chip-sequence signal, for detecting thethird spread-spectrum signal as the third plurality of detectedspread-spectrum signals, respectively.
 91. The MIMO system as set forthin claim 37 with said plurality of despreading devices including afourth filter matched to a fourth chip-sequence signal, for detectingthe fourth spread-spectrum signal as the fourth plurality of detectedspread-spectrum signals, respectively.
 92. The MIMO system as set forthin claim 39 with said plurality of despreading devices including a fifthfilter matched to a fifth chip-sequence signal, for detecting the fifthspread-spectrum signal as the fifth plurality of detectedspread-spectrum signals, respectively.
 93. The MIMO system as set forthin claim 41 with said despreading means including a first filter matchedto a first chip-sequence signal and a second filter matched to a secondchip-sequence signal, for detecting the first spread-spectrum signal andthe second spread-spectrum signal as the first plurality of detectedspread-spectrum signals and the second plurality of detectedspread-spectrum signals, respectively.
 94. The MIMO system as set forthin claim 42 with said despreading means including a third filter matchedto a third chip-sequence signal, for detecting the third spread-spectrumsignal as the third plurality of detected spread-spectrum signals,respectively.
 95. The MIMO system as set forth in claim 43 with saiddespreading means including a fourth filter matched to a fourthchip-sequence signal, for detecting the fourth spread-spectrum signal asthe fourth plurality of detected spread-spectrum signals, respectively.96. The MIMO system as set forth in claim 44 with said despreading meansincluding a fifth filter matched to a fifth chip-sequence signal, fordetecting the fifth spread-spectrum signal as the fifth plurality ofdetected spread-spectrum signals, respectively.